(a) Field of the Invention
The present invention relates to a system of removing a film material and particles left at the periphery of a semiconductor wafer, and in particular, to a plasma etching chamber capable of completely removing a film material and particles left and deposited at the periphery of the dry etched wafer during plasma etching, and a plasma etching system using the same.
(b) Description of Related Art
For the fabrication of an integrated circuit, thin film process and dry etching process are very important but the film material is unnecessarily deposited at the periphery of the wafer during the thin film process, and in addition, with the dry cleaning of the top surface of the wafer through plasma etching, the by-product generated during the plasma etching is not completely exhausted, but deposited throughout the top, the lateral and the bottom sides of the periphery of the wafer as particles.
That is, with the plasma-etched wafer, as shown in FIG. 12, particles 93 are deposited at the peripheral end of the wafer 91 continuously from the top thereof to the bottom through the lateral side, and intruded to the gap between the wafer 91 and a stage 95.
The periphery of the wafer is not used to form a semiconductor chip, but the film material and the particles left thereat (referred to hereinafter as the “particles”) cause serious damages to the semiconductor chips during the subsequent semiconductor processing steps.
The particles deposited at the peripheral end of the wafer may be removed through wet cleaning, but the wet cleaning is liable to induce other device failures with the cleaned semiconductor. The remnant solution remained after the cleaning has a high reactivity as an environmentally bad polluting material, and hence, it is difficult to waste-dispose the solution.
Japanese Patent Laid-open Publication No. Hei07-142449 discloses a device for plasma etching to remove the particles left at the peripheral end of the wafer.
With the disclosed etching device, a reaction gas is blown to the space between top and bottom electrodes arranged corresponding to the periphery of the wafer to make the plasma etching, and an inert gas is blown to the center of the top electrode to prevent the generated plasma from being intruded to the wafer.
However, as the above device has a structure of applying radio frequency to the top electrode facing the wafer while not applying the self bias to the wafer, it involves slow etching speed and long processing time.
Moreover, the etching is performed only with respect to the top surface of the periphery of the wafer so that the particles deposited throughout the lateral to the bottom sides thereof cannot be completely removed.